1. Field of the Invention
The present invention relates generally to honeycomb cores which are designed to absorb energy by deforming on impact. Energy absorbing honeycomb cores are used in a wide variety of applications including crash pads which are placed at various locations within a vehicle to reduce injuries caused when occupants hit interior surfaces of the vehicle during a crash. More particularly, the present invention relates to methods for controlling the crush properties of such honeycomb.
2. Description of Related Art
There has been and continues to be major effort to develop and design vehicle interiors which protect occupants as much as possible during the extreme forces experienced during crashes. One approach has involved the placement of crash or crush pads at various locations within the vehicle interior. The crash pads are designed to absorb the energy of impact as the occupant contacts the vehicle interior during a crash.
Initial crash pads were made from elastomeric materials, such as rubber, or from foamed plastics. Although these materials provide some protection, they are not particularly efficient and they may release stored energy during impact. This release of stored energy, commonly referred to as "rebound," can actually exacerbate injuries suffered during a crash. In addition, foam products suitable for use as crash pads tend to be bulky. As a result, they are not well-suited for use in vehicle interiors where space is limited. In order to reduce the bulk of foamed plastics, they must be made to high densities. However, such high density foams tend to be difficult to manufacture.
Honeycomb structures have been used in crash pads as an alternative to elastomers and foams. Honeycomb structures are advantageous because they are capable of efficiently absorbing large amounts of energy. One example of a honeycomb-based crash pad is disclosed in U.S. Pat. No. 5,649,721. The crash pad is designed for aircraft interiors and utilizes an aluminum honeycomb as the basic energy absorbing material.
In addition to crash pads used on the interior of vehicles, honeycomb has been used as the principal energy absorbing element in a wide variety of other applications. For example, crash cushions employing honeycomb cores have been mounted to the rear of highway maintenance vehicles to provide impact protection. Also, honeycomb crash cushions may be employed as barriers around highway structures or in any other situation where absorption of impact energy is desired.
The crush properties of the honeycomb are important characteristics which must be taken into consideration when designing a crash pad or crash cushion. The materials used to make the honeycomb, as well as the honeycomb shape and wall thickness, may be varied considerably to achieve different types and degrees of crush properties. However, in many situations, it is desirable to fine tune or otherwise control crush properties to achieve specific crush characteristics for the honeycomb. Such fine tuning and control of the crush properties may be difficult or even impossible to achieve by varying material types and/or honeycomb cell shape and wall thickness.